This invention relates to guide bearing devices for rotary shafts of high speed of rotation, and more particularly to guide bearing devices of the type described provided with cooling pads designed to prevent scattering of lubricating oil and increase the cooling effect of the bearing.
In vertical rotary machines such as hydraulic water turbines and generators, there has in recent years been a tendency toward larger sizes for increasing the capacity per machine, and rotary shafts of such machines are rotated at high peripheral velocities under high load. Oil film lubricating bearings support such rotary shafts by causing dynamic pressure produced in lubricating oil due to rotation of the rotary shaft to act as oil film pressure in a bearing gap between the rotary shaft and the bearing. Segmented bearings for guiding a vertical rotary shaft are known as oil film lubricating bearings which comprise a plurality of segmental pivoted bearing pads arranged circumferentially equidistantly around the rotary shaft and a plurality of adjusting screws each having a spherical-shaped end adapted to abut against a supporting plate of each segmental pad. In vertical rotary machines of large size, a rotary shaft rotates at high peripheral velocity to cause scattering of lubricating oil or violent undulation of the surface of lubricating oil. As a result, lubricating oil film will become broken between the rotary shaft and the bearing, or temperatures of the lubricating oil or bearing will rise, thereby rendering the performance of the bearing unstable. Scattering of lubricating oil will grow in intensity with an increase in the peripheral velocity of rotary shafts to produce a mist of lubricating oil, thereby causing leakage of the oil leading to environmental pollution in and around the equipment. Various proposals have been made to solve these problems. For example, Japanese Utility Model Publication No. 19683/67 discloses a segment type guide bearing which comprises a plurality of segmental pivoted bearing pads each having a sliding bearing surface formed with an oil groove for introducing therethrough a fresh supply of cold lubricating oil thereto. With the arrangement of the Publication, however, the sliding surfaces of segmental pads and the outer peripheral surface of the rotary shaft are spaced apart from one another by a small gap, so that lubricating oil introduced to the sliding surfaces of segmental pads through the oil grooves is limited in amount. If insufficient lubricating oil is introduced, the result will be an insufficient cooling effect. In addition, the oil grooves in the bearing described above are formed in the precisely finished sliding surfaces of segmental pads.